1. Field of the Invention
This invention relates to methods and apparatus for production of pyrolysis oils, gaseous matter, charred carbon, zinc, and filler materials from synthetic or natural rubber and rubber vulcanizates, particularly, used old tires (referred to hereinafter as scrap rubber) by traveling fluidized bed distillation. Waste rubber disposal is a critical problem due to the huge amounts generated every year, and the lack of acceptable and economical means to recycle or convert the waste rubber into valuable products. Only a small portion of the waste tires are retreaded, and a very small portion is devulcanized by tedious processes, usually in batches. Some of the scrap tires are buried in landfills or completely burned. Neither method has gained popular acceptance because the waste tires make poor landfill, and they do not readily degrade. Combustion of waste tires is difficult to accomplish without creating environmental pollution problems.
2. Description of Prior Art
A number of processes are known for the production of pyrolysis oils and other products by the thermal decomposition of rubber vulcanizates. These processes differ from each other in the manner of heat supply, heat transfer, use of devulcanizing agents, introduction of oxygen for oxidative distillation, size requirements of feed materials, and methods of feeding and removal of residue. One of the disadvantages in the known processes is the formation of coke, which hinders production. Numerous interruptions are necessary in the process in order to free the apparatus from the coke. These methods are not geared for high production and tend to be less practical as the disposal of waste tires and similar rubber products increases every day. The present invention provides for economical and acceptable environmental means for disposal of waste tires and rubber products, and it also provides for recovery of valuable products.
U.S. Pat. No. 4,030,984 discloses the method and apparatus by which the whole tires are suspended in hot gases, melting the carbonaceous material and converting it into raw material.
U.S. Pat. No. 3,890,141 discloses a method to heat treat scrap tires to produce a fluid material which, in turn, is burned to produce heat energy. The ash in the flue gases is collected by high efficiency air cleaning devices for recovery, and the ash is further processed to recover the zinc and titanium.
U.S. Pat. No. 3,823,223 disclosed the method to produce char from the destructive distillation of scrap synthetic rubber for use in rubber enforcement.
U.S. Pat. No. 3,582,279 discloses a method and apparatus for oxidative distillation of rubber vulcanizate by partial combustion of waste rubber, using air throughout the still or retort.
Bureau of Mines Report of Investigation 7302, "Destructive Distillation of Scrap Rubbers," September, 1969, discloses the gaseous, oil, and carbonaceous materials produced from different waste rubber compositions, and at different distillation temperatures. The study identifies the different compounds produced and their percentages.